nice -- run a command at a different scheduling priority


nice [ -n increment ] command [ argument ... ]

nice [ -increment ] command [ argument ... ]


The nice command is used to execute a command at a different scheduling priority than usual. Each process has a nice value which is used to calculate its priority. Nice values range from 0 to 39, with higher nice values resulting in lower priorities. By default, when nice is not used, commands have a nice value of 20. nice executes command with a nice value equal to 20 plus increment. If no increment is specified, a value of 10 is assumed giving a nice value of 30.

The preferred syntax for invoking nice is to use the -n option to specify the increment. The older form (using -increment) is obsolete but still supported. Using the older form of the command, root can run commands with priority higher than normal by specifying a negative increment. For example, an argument of --10 would decrement the default nice value of 20 by 10 to produce a nice value of 10. This nice value will give a process a higher scheduling priority than the default nice value of 20. Using the new form of the syntax, the increment to the nice value would be specified as -n -10.

Only root may specify a negative value for increment.

You can use the -l and -o nice options to the ps(C) command to display the nice value of a process.

Exit values

nice returns the exit status of command. Otherwise, it exits with one of the following values:

a usage error of nice

command was found but could not be invoked

command could not be found


Compress large.file with a nice value of 24:

nice -n 4 compress large.file


If the default nice value plus increment is larger than 39, a nice value of 39 will be used. If a nice value less than zero is requested, zero will be used.

Note also that this description of nice applies only to programs run under the Bourne Shell. The C-Shell has its own nice command, which is documented in csh(C).

By default, background jobs run by the Bourne and Korn shells are assigned a nice value four greater than that of the parent shell. The ksh(C) option +o bgnice disables this behavior, causing background processes to run with the same nice value as the parent shell.

See also

csh(C), ksh(C), nice(S), nohup(C), ps(C), renice(C)

Standards conformance

nice is conformant with:

ISO/IEC DIS 9945-2:1992, Information technology - Portable Operating System Interface (POSIX) - Part 2: Shell and Utilities (IEEE Std 1003.2-1992);
AT&T SVID Issue 2;
X/Open CAE Specification, Commands and Utilities, Issue 4, 1992.

© 2003 Caldera International, Inc. All rights reserved.
SCO OpenServer Release 5.0.7 -- 11 February 2003